In vehicle computer systems, the slot for a storage device, such as a memory card, memory stick, or Secure Digital (“SD”) card, is not typically disposed on the main printed circuit board (“PCB”), but arranged on the operation panel and connected to the main PCB via an extension line.
Typically, the transmission speed of electric current in different conductors may vary, and may generally lie in a range from 2×108 m/s to 3×108 m/s. Consequently, a wire with a length of 1 m can incur a delay of 4-5 ns, which can be doubled over the signal round trip for a total delay of 8-10 ns. The increased time may then cause sampling deviations of the storage device. The presence of the extension line may increase the signal propagation delay and the signal interference probability, which can cause compatibility issues with some storage devices. Existing solutions include down conversion, in which the clock frequency of the storage device is lowered from 50 MHz to around 12 MHz, resulting in significant reduction in the transmission speed of the storage device and deterioration in storage and system performance.